# CVE-2019-19271: Security feature bypass in n/a

> A logic error in ProFTPD's CRL verification allows revoked client certificates to be accepted, bypassing security controls when CRLs are configured.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 Nov 2019
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2019-19271, GHSA-h7h2-5q94-rr6j, UBUNTU-CVE-2019-19271

## What is CVE-2019-19271?

CVE-2019-19271 is a high-severity vulnerability in n/a, published on 26 Nov 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered in tls_verify_crl in ProFTPD before 1.3.6. A wrong iteration variable, used when checking a client certificate against CRL entries (installed by a system administrator), can cause some CRL entries to be ignored, and can allow clients whose certificates have been revoked to proceed with a connection to the server.

Weakness: CWE-295 (Improper Certificate Validation)

## Which versions are affected by CVE-2019-19271?

It affects 1 product.


Products: Proftpd Proftpd.

## How do I fix CVE-2019-19271?

Upgrade to a fixed version.

## Is CVE-2019-19271 being exploited?

There is no known exploitation of CVE-2019-19271 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2010-4221](https://insights.sbomify.com/CVE-2010-4221/): Memory corruption in n/a (critical 10.0)
- [CVE-2010-20103](https://insights.sbomify.com/CVE-2010-20103/): ProFTPD 1.3.3c Backdoor Command Execution (critical 9.3)
- [CVE-2011-4130](https://insights.sbomify.com/CVE-2011-4130/): Use after free in n/a (critical 9.0)
- [CVE-2026-63090](https://insights.sbomify.com/CVE-2026-63090/): ProFTPD mod_sftp Heap Buffer Overflow via SFTP Packet Reassembly (high 8.7)
- [CVE-2026-35025](https://insights.sbomify.com/CVE-2026-35025/): ProFTPD ACL Bypass via /proc/self/root Path Prefix in RNFR (high 8.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-19271 and fix it if it is affected.

What it is: CVE-2019-19271 is a high-severity vulnerability in n/a, published on 26 Nov 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2019-19271 in the wild and no public exploit code.

Affected product: n/a. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2019-19271/ (Markdown: https://insights.sbomify.com/CVE-2019-19271/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-19271
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-19271
- OSV: https://osv.dev/vulnerability/CVE-2019-19271

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-19271/
Summaries are generated and may contain mistakes; the official description above is the record.